A coarse wood dynamics model for the Western Cascades.

Abstract

The Coarse Wood Dynamics Model (CWDM) analyzes the dynamics (fall, fragmentation, and decomposition) of Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) snags and down logs in forested ecosystems of the western Cascades of Oregon and Washington. The model predicts snag fall, height loss and decay, and log decay at 5-year intervals for a period of 300 years. Snags either fall whole or in parts, creating down logs. Snags also decay from a hard to soft condition. Logs decay more slowly than snags, from sound to decayed conditions, and eventually disappear into the forest floor as duff. Snag fall and height loss rates were derived from Forest Inventory and Analysis (FIA) remeasurement data on private lands in western Washington. Decay rates were obtained from various studies conducted in the western Cascades of Oregon and Washington. The model can track remnant snags and logs (i.e., those existing on site at the beginning of the assessment time) and new snags and logs created from green trees.

Citation

Mellen, K.; Ager, A. 2002. A coarse wood dynamics model for the Western Cascades. In: Proceedings of the symposium on the ecology and management of dead wood in western forests. 1999 November 2-4; Reno, NV. Gen. Tech. Rep. PSW-GTR-181. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 503-516